Answer:
12.4g of water has 0.689 moles of water.
Explanation:
Molar weight of 
= 16 + 2 = 18g
One mole of weighs 18g.
Hence, 12.4g of water has 0.689 moles of water.
Answer:
15 mL of 15% acid solution and 30 mL of 3% acid solution
Explanation:
The total number of moles of the mixture 
is equivalent to the addition of the number of moles of the first solution 
and the number of moles of the second solution 
. Mathematically,
The volume of the mixture = 45 mL
The volume of first solution = x
The volume of second solution = 45 - x
Therefore:
0.15x + 0.03(45-x) = 0.07*45
0.15x + 1.35-0.03x = 3.15
0.12x = 1.8
x = 15
Thus, the volume of the first solution is 15 mL while the volume of the second solution is 30 mL.
Answer:
A. light energy is used in photosynthesis and created by respiration
The generalized rate expression may be written as:
r = k[A]ᵃ[B]ᵇ
We may determine the order with respect to B by observing the change in rate when the concentration of B is changed. This can be done by comparing the first two runs of the experiment, where the concentration of A is constant but the concentration of B is doubled. Upon doubling the concentration of B, we see that the rate also doubles. Therefore, the order with respect to concentration of B is 1.
The same can be done to determine the concentration with respect to A. The rate increases 4 times between the second and third trial in which the concentration of B is constant, but that of A is doubled. We find that the order with respect to is 2. The rate expression is:
r = k[A]²[B]
